I'm gonna go out on a limb and say you have a stant thermostat - remove it, take one last look at and chuck it as far as you can
Stants suck major ass, at least in toyotas. Get a quality replacement and install it. If you have a good thermostat you should never have to drill a hole in it. My current one is a beck arnley I think, which was installed after going through a
pile of stants - and don't EVER buy a stant no-fail. They're supposed to lock in the open position if they ever mess up, but mine locked shut just after I bought it
